Deferred action type gas depolarized dry cell having prolonged shelf life



Sept. 2, 1952 G. w. HEISE ETAL DEFERRED ACTION TYPE GAS DEPOLARIZED DRY CELL HAVING PROLONGED SHELF LIFE Filed Feb 19, 1949 A All INVENTORS GEORGE W HEI RUSSELL P.- 0X

BY A'T ORNEY Patented Sept. 2, 1 952 s nn cnscr o -ra G Sl E AR?" IZED DRY CELL HAVING PROLONGED-V SHELF LIFE George W. Heise, Rocky Rivenand Russell P. Fox,

Cleveland o hio, assignors, by mesne assign-. ments, to Union Carbide and Carbon Corpora- T tion,a corporation of New York 7 Application February 19,1949, Serial No. 77,392

This invention relates to a deferred action, gas depolarized dry cell and has for an object to improve the performance characteristics of such a cell after a period of storage.

In a preferred form of such a cell and battery of them, there is a casing hermetically enclosing the battery in a partial vacuum or in an oxygenfreeatmosphere of inert gas. Variations in external temperature encountered in normal stor- 8 Claims. (01. 136-'-8) the present inventionhas enhanced theirTshelf life, enabling them to be stored for at least six months under the same conditions of variable temperature without significant deterioration. After precipitation of moisture within the casing and upon a rise in external temperature or the attainment of vapor pressure equilibrium, irrespective of temperature,- transfer of moisture to the cells takes place at a rapid rate from a age, such as that between day and night, cause 10 saturated bibulous liner and more rapidly from sufficient loss of moisture from the cell, after a the highly developed surface of a bibulous fibrous prolonged storage period, to impair the cell liner than it would from individual droplets or a efficiency through increase in internal resistance, small pool, and the cells remain in operating deterioration of electrode-immobilized electrocondition for indefinitely prolonged periods of lyte contact, and general lowering of overall catime. Of great importance, further, is the fact acity. The most rapid loss in moisture was h t. in h a fic f th liner, Subsequent found to be from the wet portion of the evaporation of water collecting at the bottom of cathode, although some was found to be from the container will result in transfer of moisture the immobilized electrolyte through the diffuser sooner and in larger quantity to the lower than portion of the cathode. A number of temperato themoreremote portionsoi thebattery, causture drops on succeeding nights caused de'posi- 'ing transient inequalities in" moisturev content tion of moisture at the bottom of the casing. which may seriously affect cell operation and Subsequent rises in temperature during the days shelf quality. 1 The liner may, be wet or dry did not succeed in getting all the moisture back init through a linermoistened with water or into the cell. electrolyte is-preferred. The weaker the solu- According to this invention, a Way has been 1 tion; O Electrolyte in t e lin t e mo rapid discovered for retarding; the loss of moisture will be thetransfer of moistureintothe cells. from the cells and for accelerating the uniform R f n to h ingle figureof t e draw return of condensate to the cells from the dethe drawing illustratesa deferred cti n p posited moisture inthe enclosing casing. Spay t y of the r described in h Said cifically, this has been accomplished by prop m patent 1 of Zimmerman and C'ahoon, viding a large area surfaceof bibulous and, also, 5 22 dated October 23, 195 for Primary preferably fibrous, material inside the casing. C l and Battery and Method of Making Same, Such surface is preferably arranged as a liner f w h the present, invention an im for the casing sides, top, and bottom. This liner merit. V l should desirablyw contain suflicient moisture A battery of WO 7 5 is r ted t it will either as water or as electrolyte to saturate. the be r tood that; any-num rrof 0811's y be atmosphere inside the casing prior to suchsaturus fi d i t0 the, voltage desired from the ation by the liquid of the cells and thus reduce battery.- Each cell comprises-a zinc anode It conevaporation of liquid from the battery cells. 40 tie o s-w W chan mmo i electrolyte After precipitation on a temperature drop out- "layer U a githe anode- 10 of a cell from side thecasing, the precipitatedmolsture is abits ca h l fli p plates 13 nd I4 sorbed by the iner and, better available to be reera y of in a g, material h l the b tturned to the cells after equilibrium in vapor fi y, elements under a p s v str ss exerted pressure. is reached or during a subsequentinby he p n bolts 15 extending between t e v creasein, temperatuream resaturation of the p l rm n lle dslfi and I! con- :cas ing atmosphere atthehigher temperature. d c c renti mrth v ry rough bushings Where the'prior cells, such as those described il-lus r ed'iniEhalE DiOf; the battery asin A inthe application of Zimmerman and Cahoon, p destal suppor .18, preferably of. insulating Serial No. 53,174, filedoctober f7, 1948, now- U. s. mat rial carries the; battery' t t ea h f t Patent 2,5 '7 2',296 granted October 23, l'95l for various cell elements isoutof. contact with such Primary Cell and Battery and. Method of Maksupport, thus .enabling-jgasrwithin the casing to ing same, could be. deteriorated in periods, debe; brought intdintimatei contact; with the oathpending on the variation of the storage tempera- "odeiofz'eiacrt cell; 5-; ;-T' 1 1 ,7 ture, of from a few weeks to perhaps two months, The enclosing Casing I9 is pr i ed with a cover 20, and bolts 2| pivotally secured to the casing I9 hold the cover in place, clamping a gasket 22 between the cover 20 and casing H. An inlet pipe 23 controlled by a shut-off valve 24 conducts depolarizing gas to the battery casing when the battery is to be actuated and an outlet passage from the casing as shown in the aforementioned patent of Zimmerman et a1. may or may not be provided.

A liner 32 of fibrous bibulous material such as blotting paper or more especially filter paper, such as Eaton & Dikeman #608, covers all interior walls of the casing. The liner might be temperature there will for a while, or until some appropriately absorptive material such as flock sprayed against the inside of the casing. This lining material 32 is impregnated with a regulated amount of moisture of a solution of controlled vapor pressure, prior to the casing being closed and hermetically sealed. The moisture in the bibulous liner 32 has a far larger portion of its surface exposed than does moisture in the battery cells. Since the moisture in the lining has a higher vapor pressure than that in the battery cells, as well as a larger area, the moisture from this liner 32 will evaporate until the atmosphere within the casing is substantially saturated, leaving the cell relatively unchanged. When that is so there is no tendency for moisture from the cell to be evaporated so that the shelf life of the cell is greatly prolonged. Upon any increase in temperature of the casing, the bibulous sheet 32 is adapted to give up more of its moisture to the casing atmosphere. When the casing increases in temperature moisture evaporates and condenses on the cells, which are cooler. This action tends to heat up the battery cells and to create temperature equilibrium. In event of drop in temperature and condensation of moisture from the gas within the casing, such moisture is condensed-on the liner 32. Thus characteristics of the liner are its large capacity for moisture so that moisture does not quickly deposit in droplets and collect in the bottom of thecontainen'its ability to pass moisture from one part to another so that it is substantially uniformly wet as long as any part of it contacts with any water collected in the bottom of the container, and its large exposed surface area so that moisture is rapidly given up by the liner to the casing atmosphere. mosphere becomes uniformly separated from the liner the shelf life of the battery is greatly prolonged by reason of the fact that moisture returns to the battery, as stated previously, and

there is no further tendency for moisture to be vaporized from the battery element. I

Among the advantages of this invention may be mentioned-the increase in battery shelf life of substantially 2000% from the present invention which prevents the battery cells from becoming dried out as was found to happen prior to the present invention, through maintenance of a relatively stable moisture condition in the cell or battery. The provision of a liner of highly developed surface facilitates uniform moisture When the casing atvapor pressure, etc.

distribution. The liner being a moist porous mevection, or radiation, but is lost by evaporation of water, which condenses on the inside. of the an equilibrium in vapor pressure is reached, be a transfer of moisture to the cells, due to the larger area of the liner and higher vapor pressure of moisture in the lining. Having the liner wet with a weaker electrolyte solution than is used in the wet mix portion of the cathode creates a tendency for the electrolyte solution in the cells and in the liner to become equalized in strength. The moisture from the liner dilutes the electrolyte in the cells, which is one reason for controlling the amount of moisture initially placed in the liner. The total moisture in the liner may be substantially less than that in the cathodes and the smaller amount of moisture in theliner is sufiicient due to its large exposed surface, At a constant temperature, when the atmosphere in the casing has not been saturated, there is more tendency for moisture to be taken from the liner than from the cell due to area and greater vapor pressure. A partial vacuum in the casing is useful in expediting activation of the cell on the admission of chlorine, but such reduced pressure is objectionable by facilitating interchange of moisture due to temperature differences such as may exist between those during the day and those at night. Instead of a partial vacuum, an atmosphere of inert gas such as nitrogen within the casing has been found advantageous in retarding the interchange of moisture due to temperaturediiferences, provided the inertgas is evacuated from the casing before the depolarizing gas is introduced or is adapted to be swept to one side and not retard actuation of the battery, Before being placed in the cell ready for use, the filter paper liner mentioned above or other bibulous lining is preferably dried at to C. for several hours and stored adjacent calcium chloride until ready for use in the cell. The. necessary water or other solution may be added to the liner by rolling another damp bibulous sheet, such as blotting paper, with a glass cylinder, orby pressurewhen the filter paper'is placed next to the damp sheet, or in case of ab'ibulous liner. sprayed {onto inner surface by steaming or spraying with solution of desired To reduce the possibility of anode corrosion occurring during storage, the atmosphere in the casing should be free of oxygen, because if such ispresent it mightactas a depolarizer. 1 What is claimedis: 1'. A deferred action dry fcellhaving an enclosed casing outside of. and spaced from said cell on more. than'one side hermetically sealing the cell, at least one/element of .the cell contaming moistureandbeing exposed'to the casing atmosphere between the cell] and casing, and a bibulous material outsideof the cell and spaced fror'n ithe moisture containing cell element, havalargerexposed surface than the exposed surfaceof the cell Within the casing whereby moisture from the-bibulous materialmay. spread any deposit of moisture-over its surface and tend to saturate the atmosphere within the casing and parade-P e- "99 b). A

2. A dry cell according to claim 1 in which said bibulous material is in sheet form secured on at least the bottom of the cell casing.

3. A deferred action type dry battery having an enclosing casing hermetically sealed and provided with an opening into which depolarizing gas is adapted to be supplied, the battery having moisture containing elements at least partially exposed to any gas outside of the battery and within the casing, a bibulous sheet in addition to said battery and spaced therefrom on more than one side, of larger exposed area than the exposed area of the moisture containing elements and extending over at least a portion of the casing interior, moisture in said bibulous sheet partially but not entirely filling the said sheet whereby said sheet is adapted either to absorb condensed moisture from any gas in the casing or to supply moisture to such gas by vaporization.

4. A battery according to claim 3 in which the bibulous sheet extends on the inside of all walls of the battery casing.

5. A battery according to claim 4 in which said bibulous sheet is absorbent paper containing about 20% to 30% by weight of moisture when inserted and sealed in said casing.

6. A deferred action type gas depolarized dry battery having an enclosing casing hermetically sealed surrounding and spaced from the battery and provided with an opening into which depolarizing gas is adapted to be supplied, the battery having moisture containing elements at least the edges of which are exposed to any gas within the casing and outside the battery, and a bibulous sheet material in said casing outside of said battery, partially filled with moisture and capable of saturating any gas within the casing.

'7. A deferred action type gas depolarized dry battery having an enclosing casing hermetically sealed and spaced at least in two directions from said battery and provided with an opening into which depolarizing gas is adapted to be supplied, the battery having moisture containing elements the shelf life of said cell, said improvement comprising a bibulous material within said casing but outside of said cell, spaced from it, and impregnated with a weaker solution of electrolyte than that electrolyte solution in said moisture containing element whereby said bibulous material is adapted to receive moisture deposited from any gas within the enclosing casing on a drop in temperature external to the casing and whereby said bibulous material is adapted to contribute more moisture to any gas within the casing on a rise in temperature than is the cell.

I GEORGE W. HEISE.

RUSSELL P. FOX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,032,529 Burgess et al July 16, 1912 2,266,686 Emanuel Dec. 16, 1941- 2,272,744 Helling Feb. 10, 1942 2,312,463 Zdansky Mar. 2, 1943 FOREIGN PATENTS Number Country Date 540,984 Great Britain Nov. 25, 1940 

1. A DEFERRED ACTION DRY CELL HAVING AN ENCLOSED CASING OUTSIDE OF AND SPACED FROM SAID CELL ON MORE THAN ONE SIDE HERMETICALLY SEALING THE CELL, AT LEAST ONE ELEMENT OF THE CELL CONTAINING MOISTURE AND BEING EXPOSED TO THE CASING ATMOSPHERE BETWEEN THE CELL AND CASING, AND A BIBULOUS MATERIAL OUTSIDE OF THE CELL AND SPACED FROM THE MOISTURE CONTAINING CELL ELEMENT, HAVING A LARGER EXPOSED SURFACE THAN THE EXPOSED SURFACE OF THE CELL WITHIN THE CASING WHEREBY MOISTURE FROM THE BIBULOUS MATERIAL MAY SPREAD ANY DEPOSIT OF MOISTURE OVER ITS SURFACE AND TEND 